[Ni(L)(MeCN)][BF4]2 {L = 2,5,8-trithia[9],(2,9)-1,10-phenanthrolinophane} as a building block for the synthesis of binuclear nickel(ii) complexes: X-ray crystal structure and magnetochemistry of a singly F-bridged nickel(ii) dimer

Abstract

The substitution reactions of the coordinated acetonitrile molecule in [Ni(L)(MeCN)][BF₄]₂ (1) {L = 2,5,8-trithia[9],(2,9)-1,10-phenanthrolinophane} with three potentially bidentate ligands L′ (L′ = N₃⁻, 4,4′-bipyridine and F⁻) have been studied both in solution and in the solid state with the aim of verifying the potential of 1 as a starting material for the synthesis of [{Ni(L)}₂L′]ⁿ⁺ (n = 3, 4) Ni^II-binuclear compounds. While the mononuclear [Ni(L)(N₃)]BF₄ complex was isolated in the solid state from the reaction of 1 with N₃⁻, the binuclear [{Ni(L)}₂F][BF₄]₃·MeCN·H₂O and [{Ni(L)}₂(4,4′-bipy)][BF₄]₄ compounds have been obtained from the reactions of 1 with F⁻ and 4,4′-bipy, respectively. The first two complexes have been characterised by X-ray diffraction studies. In [Ni(L)(N₃)]⁺, a distorted octahedral geometry is achieved at the Ni^II, with five sites occupied by the macrocyclic ligand L and the sixth by a monodentate azide group. In [{Ni(L)}₂F]³⁺, two [Ni(L)]²⁺ units are bridged by a fluoride ligand to give only the second example of a singly F-bridged Ni^II dimer. The magnetisation of [{Ni(L)}₂F][BF₄]₃·MeCN·H₂O and of [{Ni(L)}₂(4,4′-bipy)][BF₄]₄ has been recorded over the temperature range 1.8–300 K and indicates a significant antiferromagnetic exchange in the former.